A-sulfinyl p-toluenesulfonamide

Later on, Christensen (134,135) showed that the reaction of chiral sulfoxides with A -sulfinyl-p-toluenesulfonamide in benzene as well as... 

One synthetic problem in aza Diels-Alder reactions is the stability of imines under the influence of Lewis acids. It is desirable that the Lewis acid-activated imines are immediately trapped by dienes or dienophiles. In 1989, Sisko and Weinreb reported a convenient procedure for the aza Diels-Alder reaction of an aldehyde, a 1,3-diene, and A-sulfinyl p-toluenesulfonamide via A -sulfonyl imine produced in situ—a stoichiometric amount of BF3 OEt2 was used as a promoter [28a]. 

In the reaction of A-sulfinyl-p-toluenesulfonamide with methyl-t-butylcarbodiimide, the reaction proceeds across the less sterically hindered C=N bond to give methyl A-sulfinylamine and A-p-toluenesulfonyl-A -t-butylcarbodiimide-. ... 

In this article a differentiation of concerted and two-step cycloadditions will not be made although this point will be briefly discussed in the theoretical part. However, products which could be formally formed by a hetero Diels-Alder reaction, but for which a different mechanism has been proven will not be included. Thus, quite recently it has been shown that the formation of an oxazine by reaction of N-sulfinyl-p-toluenesulfonamide and an excess of propanal in the presence of boron trifluoride etherate does not involve a hetero Diels-Alder reaction [37]. 

Despite a considerable amount of recent work on reactions of vinyl silanes with various kinds of imines [48,49], scant attention has been paid to N-sulfonyl imi-nes in this area. A single study of a vinyl silane/N-sulfonyl imine reaction has been published by McIntosh and Weinreb in the context of an approach to the total synthesis of [1, 3]-dioxolophenanthrene structural types of Amaryllida-ceae alkaloids such as narciclasine (137), lycoricidine (138) and pancratistatin (139) [50]. The substrate used in this approach was vinyl silane aldehyde 140, prepared enantiomerically pure in a straightforward manner from L-arabinose (Scheme 26). The N-tosyl imine derived from this aldehyde could be generated in two different ways. The first involved combination of 140 with N-sulfinyl-p-toluenesulfonamide at 80 °C, followed by exposure of the imine to BF3 etherate at 0°C, leading to a single cyclization product 142 in 36% yield. The second procedure was to simply react aldehyde 140 with p-toluenesulfonamide and BF3 etherate (-78°C -rt) to afford a 9.5 1 mixture of 142 144 in -80% yield. It was pro-... 

Mock and Nugent investigated the mechanism of the [4 + 2] cycloaddition of iV-sulfinyl-p-toluenesulfonamide (9) and the isomeric 2,4-hex-adienes 10,11, and 12 in detail (Scheme l-II).11 These workers determined the relative stereochemistry of the resulting adducts and proposed a stepwise dipolar mechanism based primarily on the difference in sulfur stereochemistry between adducts produced from dienes 11 and 12. 

Hofmann s classical synthesis of 3,5-disubstituted 1,2,4-thiadiazoles by the oxidation of thioamides (1869)3 continues to be further exemplified. The oxidants employed include iodine,9-11 bromine,12 chlorine,13 and nitrous acid,14 as well as /V-chlorobenzamidine (which is recovered as benzamidine)15 and IV-sulfinyl-p-toluenesulfonamide (which evolves sulfur dioxide in the process).16 Irradiation with UV light in the presence of oxygen effects the same reaction, but has not been used on a preparative scale.17... 

The A -SES group can be incorporated by treating an aldehyde with (V-sulfinyl-p-trimethylsilylethanesulfonamide (SESNSO) (13), which can be made by treating the sulfonamide (12) with Thionyl Chloride and a catalytic amount of N,N-dichloro-p-toluenesulfonamide (eq 7) (see also N-Sulfinyl-p-toluenesulfonamide). The )V-sulfonyl imine can be used in situ in a number of reactions. For example, the A(-sulfonyl imine from aldehyde (14) reacts with 2,3-dimethylbutadiene (eq 8) to give the Diels-Alder adduct (15). Treatment of (15) with fluoride ion affords the bicyclic lactam (16). Also, the IV-sulfonyl imine derived from isobutyraldehyde and (13) reacts with Vinylmagne-sium Bromide to provide the allylic SES-sulfonamide (17) in 65% yield (eq 9). ... 

Form Supplied in bright yellow solid commercially available. Preparative Methods the most common method of preparing A-sulfinyl-/>toluenesulfonamIde (TsNSO) (1) Is by heating p-toluenesulfonamlde with excess thionyl chloride In benzene (eq ) ... 

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